Mass. Gen. Laws ch. 51 § 22A
In every city and town the registrars of voters may, before every election at which absent voting is permitted, appoint a sufficient number of absent registration officers who in addition to the registrars and the assistant registrars may attend persons claiming to have the qualifications for voting in their respective cities and towns, but who, by reason of physical disability, are unable to apply in person for registration, to examine such persons relative to their qualifications for voting and to register such of said persons as they find to be qualified. Such absent registration officers shall be appointed from the enrolled voters of their respective cities and towns and shall, as nearly as may be, equally represent the two leading political parties.
Absent registration officers appointed under this section shall, in the performance of their duties, have all the powers, and be subject to all the obligations and penalties, of registrars of voters, but their doings shall be under the direction, and subject to the revision and acceptance, of the registrars of voters.
Mass. Gen. Laws ch. 51, § 22A